JP2002296893A - Toner concentration detector, image forming apparatus or digital copying machine using the detector, magnetic body detector, and conductor detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize the inductance of a primary coil and that of a secondary coil to each other, to increase magnetic coupling between both coils to obtain a large output, and to realize miniaturization of a toner concentration detector and improvement of the detection capacity on the assumption that the primary coil of a first resonance circuit and the secondary coil of a second resonance circuit are used to detect the toner concentration. SOLUTION: A toner concentration detector is provided with a plurality of coils close to a developer containing magnetic powder called carrier and coloring particles called toner and uses these coils to detect the toner concentration indicating the mixture ratio of toner to carrier of the developer, and the coils have shapes including rectangles different in aspect ratios or ellipses. The coils are so arranged that their lengthwise direction coincides with the direction of the revolving axis of a developer stirring member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to, for example, PPC (P
line Paper Copier), LBP (La
More specifically, the present invention relates to a toner density detecting device for detecting toner density, and more particularly to a structure of a coil whose impedance changes according to toner density.

[0002]

2. Description of the Related Art In an electrophotographic copying apparatus, generally,
The surface of the photosensitive drum is uniformly charged by a charger,
An electrostatic latent image is formed by exposing the photoreceptor based on image information, toner is selectively adhered to the electrostatic latent image and developed, and the obtained toner image is transferred to plain paper and then fixed. To get the final image.

FIG. 2 shows a configuration example of a developing device. This developing device is a small-diameter two-stage developing roller system, in which an upper developing sleeve and a lower developing sleeve are arranged adjacent to the photosensitive drum,
A developer consisting of a non-magnetic toner mainly composed of a colorant and a magnetic carrier is fed to the surface of the photosensitive drum by a paddle roller. As the development is carried out, the magnetic carrier hardly decreases, but the toner decreases. Therefore, a toner hopper is provided to replenish the reduced toner, and the hopper stores the replenishing toner.

When the mixing ratio of the toner to the magnetic carrier decreases, the density of the developed image decreases, and when the mixing ratio increases, the opposite occurs. In order to obtain an image of appropriate quality, it is necessary to always maintain the toner density contained in the developing device within an appropriate constant level range. For this reason, a toner density detecting device (T sensor) for detecting the toner density in the developer )
Is installed. In addition, the developing device is provided with a stirring roller to make the mixed state of the developer and the replenishing toner uniform.

As a conventional example of a specific circuit configuration for detecting the toner density in a developing device, there is a technique disclosed in Japanese Patent Application Laid-Open No. Hei 6-289717. The magnetic detecting device for detecting the toner concentration in this publication uses a so-called differential transformer type phase difference detection.

Japanese Patent Application Laid-Open No. 2000-131120 discloses a conventional technique for stably detecting whether or not the toner amount in a toner hopper has decreased to a reference amount with high sensitivity. According to this publication, a developing device is disposed in the vicinity of a coil L1 and a coil L2 which are magnetically coupled to each other.
1 forms a first resonance circuit, L2 and C2 form a second resonance circuit, and an output from a solid-state oscillation circuit is input. Since the resonance frequency of the resonance circuit is set to be close to the oscillation frequency of the solid-state oscillator, the toner level can be detected with high sensitivity.

Further, the prior art relating to the structure of a coil for detecting toner density is described in Japanese Patent Application Laid-Open No. 58-76865. According to this publication, a ferrite having a high magnetic permeability is installed on the outside of a resin plate case facing a stirring roller in a developing device, and a coil is wound around the ferrite. The detection sensor is small and has high detection capability.

Further, Japanese Patent Application Laid-Open No. Sho 62-245152 discloses a conventional coil structure. According to this, a detection coil portion for detecting a change in the magnetic properties of the developer and a comparison coil portion are formed, and a double coil pattern is formed on one side of the plate-like insulator, and two adjacent patterns are formed. A structure is disclosed in which one of the coil patterns is arranged as a detection coil unit and the other as a comparison coil unit, and the detection coil unit is arranged in the developer tank and the comparison coil unit is arranged outside the developer tank. I have.

[0009]

SUMMARY OF THE INVENTION Prior Art
Japanese Patent Application Laid-Open No. 768865 proposes a structure in which the inductance that determines the oscillation frequency of the oscillation circuit is formed by a single turn of the coil, and the overall shape of the single turn coil including the magnetic core is reduced. It does not focus on the magnetic coupling between the secondary coil and the secondary coil.

In Japanese Patent Application Laid-Open No. 62-245152, a spiral primary coil and a secondary coil are formed as a double coil pattern on a plate-shaped insulator, and the spiral coil is wound twice. The coil pattern thus formed is formed by attaching a thin copper plate to a substrate and then performing photoetching. In this conventional technique, the coil portion is formed not by winding but by patterning on a substrate to achieve miniaturization.

An object of the present invention is to provide a method for detecting a phase difference or an amplitude change using a primary coil of a first resonance circuit and a secondary coil of a second resonance circuit in order to detect a toner concentration. An object of the present invention is to provide a large output by equalizing the inductances of the primary coil and the secondary coil and increasing the magnetic coupling between the two coils, and to reduce the size and improve the detection performance of the toner density detecting device.

[0012]

In order to solve the above problems, the present invention mainly employs the following configuration. In a toner concentration detecting device, a coil is provided in proximity to a developer containing magnetic powder called a carrier and colored particles called a toner, and a toner concentration indicating a mixing ratio of the toner and the carrier of the developer is detected using the coil. And a coil having a shape including a rectangle or an oval having different aspect ratios.

In addition, a coil is provided in proximity to a developer containing magnetic powder called a carrier and colored particles called a toner, and a toner concentration indicating a mixing ratio of the toner and the carrier of the developer is detected using the coil. In the toner concentration detection device, the coil has a shape including a rectangle or an oval having different aspect ratios, and the toner concentration is arranged such that a longitudinal direction of the coil coincides with a rotation axis direction of the developer stirring member. Detection device.

Further, a coil is provided in proximity to a developer containing magnetic powder called a carrier and colored particles called a toner, and a toner concentration indicating a mixing ratio of the toner and the carrier of the developer is detected using the coil. In the toner concentration detecting device, the coil has a U-shape in which both sides of a wound coil body having a circular, square, rectangular, or oval shape are bent.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A toner concentration detecting device according to an embodiment of the present invention will be described below with reference to the drawings. Figure 1
FIG. 1 is a diagram illustrating an outline of an electrophotographic copying apparatus to which a toner density detecting device according to an embodiment of the present invention is applied, and FIG. 2 is a diagram illustrating a configuration of a developing device provided with the toner density detecting device; FIG. 3 is a diagram illustrating a circuit configuration of the toner density detecting device according to the present embodiment, and FIG. 4 is a diagram illustrating another circuit configuration of the toner density detecting device according to the present embodiment. FIG. 5 is a diagram for explaining basic functions related to the toner concentration detecting device according to the present embodiment.
FIG. 6 is a diagram illustrating signal waveforms in the circuit configuration according to the present embodiment.

1 to 3, 1 is a reading unit, 2 is a lamp, 3 is a CCD, 4 is an amplifier, 5 is an A / D converter, 6
Denotes an image processing unit, 8 denotes a shading correction, 9 denotes a filter, 10 denotes a gamma correction, 11 denotes a gradation process, 12 denotes an image forming unit,
13 is a writing unit, 14 is an exposure, 15 is a charger, 16 is a developing sleeve, 17 is a paper feed tray, 20 is a magnetic material detection circuit, 21 is an oscillation circuit, 22 is a resonance circuit (detection circuit), and 23 is a phase comparison. Circuit, 24 is an integration circuit, 25 is an impedance conversion circuit, and 26 is a developer.

In the electrophotographic copying apparatus shown in FIG. 1, the light radiated from the lamp 2 is reflected on the document surface in the reading section 1 and converted into an electric signal by the CCD 3 in the reading section 1. A / D converter 5 after amplitude adjustment
Is digital image data quantized by. The generated digital image data is input to the image processing unit 6,
A shading correction process 8, a filter process 9, a gamma correction process 10, a gradation process 11, and the like are performed in this order and sent to the image forming unit 12.

The digital image data input to the image forming unit 12 is converted into a laser beam 14 by a writing unit 13 in accordance with the data value, and is radiated to a photoconductor charged by a charging charger 15, and electrostatically applied to the photoconductor surface. Form a latent image. The developing sleeve 16 follows the formed electrostatic latent image,
The toner is attached to the photoconductor surface. The toner adhering to the photoreceptor surface is transferred onto the paper surface sent from the paper feed tray 17, passes through the fixing unit 18, and is output as a copy original.

In the developing device shown in FIG. 2, the toner concentration in the developing device is detected and maintained at a predetermined value in order to obtain a high quality image while always keeping the mixing ratio of the toner to the magnetic carrier at an appropriate value. There is a need to. When it is detected that the toner density has dropped, control is performed so that toner for replenishment is supplied from the toner hopper and an appropriate toner density is obtained. Therefore, a toner concentration detecting device (T sensor) for detecting the toner concentration in the developer is provided.

The toner density detection circuit 20 shown in FIG. 3 has an oscillating circuit 21, a resonance circuit 22, a phase comparison circuit 23, an integration circuit 24, and an impedance conversion circuit 25 as its basic configuration. The oscillation circuit 21 oscillates using a solid-state oscillator such as a crystal or a ceramic, and the oscillation frequency is determined based on a unique frequency of the solid-state oscillator such as a crystal or a ceramic. It is hardly affected by the use environment and the power supply voltage, and enables stable and accurate detection as one component of the toner density detection.

The resonance circuit (detection circuit) 22 outputs the output from the oscillation circuit 21 to the primary coil L1 through a resistor R3.
Is input to The resonance circuit 22 includes a first resonance circuit including a primary coil L1 and a shared capacitor C3 sharing a capacitor, a secondary coil L2 coupled to the primary coil L1 with a magnetic coupling constant k, and the shared capacitor C3. A second resonance circuit. In FIG. 2, the primary coil L
A developer 26 in which a magnetic carrier and a non-magnetic toner in a developing device are mixed is disposed in a non-contact manner in the vicinity of the primary and secondary coils L2, and the substantial inductance of the coils L1 and L2 is affected by the toner concentration in the developer. give.

In the present embodiment, the capacitors of the first and second resonance circuits are shared (that is, shared and shared) and the capacitor C3 is employed, so that the values of the components of the resonance circuit vary. The difference between the primary and secondary resonance frequencies can be easily minimized by sharing a large capacitor. In addition, one of the features of the present embodiment is that the inductances of both coils can be made equal by a modified winding mode of the primary coil and the secondary coil, which will be described later. The secondary resonance frequency can be equalized, and a large phase difference output can be obtained.

Further, by using a common capacitor, resonance characteristics equivalent to those in which a capacitor is provided in each resonance circuit can be maintained, and the cost can be reduced by reducing the number of capacitors.

Further, in order to obtain a large toner density detection output, the oscillation frequency fosc of the oscillation circuit 21 and the resonance circuit 2
It is desirable to make the resonance frequencies fc of the two equal (for example, when the toner density is at the optimum value, f
In this case, the resonance frequency fc can be adjusted only by adjusting the capacitance value of the capacitor C3, and the frequency can be easily adjusted. In this case, the primary and secondary coils can easily make the inductances of both the same level easily from the devised coil structure and coil forming method.

The oscillation frequency fosc and the resonance frequency f
By making c substantially the same, a large output fluctuation value with respect to a change in toner density can be obtained (for details, see FIG. 5).
Described later), it is possible to secure a sufficient sensitivity for toner concentration detection.

Next, in FIG. 4 showing another example of the configuration of the toner concentration detecting circuit according to the embodiment of the present invention, the oscillation circuit and the separation function or oscillation are stabilized in the same manner as the circuit configuration shown in FIG. R1 having an oscillation stabilizing function for maintaining
1 and a phase difference extracting unit for extracting a phase difference output using the resonance circuit as it is.

In the configuration example shown in FIG. 4, the oscillation stabilizing function R
A first resonance circuit including a primary coil L1 and a first capacitor C1, and a second resonance circuit including a secondary coil L2 and a second capacitor C2 are provided on the downstream side of the first coil. Here, the primary coil L1 and the secondary coil L2 are coupled with a magnetic coupling constant k, and a developer 26 containing toner is arranged near and non-contact with L1 and L2. One phase difference is extracted from the connection point between the oscillation circuit and the resistor R1, and the other is the output point from the second resonance circuit.

According to the configuration example of FIG. 4, the first resonance circuit (L
, C1) and a second resonance circuit (L2,
The resonance frequency fc2 of C2) is set to be substantially the same, and an output V2 based on the integrated Q obtained by multiplying Q1 of the first resonance circuit and Q2 of the second resonance circuit is obtained. Phase difference output can be obtained.

Next, the function and operation of the phase comparison by the output from the resonance circuit side in the phase comparison circuit 23 will be described with reference to FIGS. In the graph shown in FIG. 5, the horizontal axis represents the frequency in the resonance circuit 22, and the vertical axis represents the phase difference between V1 and V2 shown in FIG. The solid line shows the phase difference characteristic with respect to the frequency when the toner density is appropriate, and the broken line shows the phase difference characteristic with respect to the frequency when the toner density is lower than the appropriate value.

When plotting the phase difference output between V1 and V2 of the resonance circuit shown in FIG. 3, the characteristics shown by the solid line and the broken line shown in FIG. 5 can be obtained (experimentally obtained data). The phase difference output shows a characteristic that greatly fluctuates in a region where the frequency to be generated matches or substantially equals the frequency fosc of the oscillation circuit. In the resonance circuit 22, the oscillation frequency fosc
When a lower resonance frequency fc is used, as is apparent from the phase difference characteristics between the solid line and the broken line shown in FIG. 5, almost no phase difference output occurs between the proper value and the reduced value of the toner density.

FIG. 6 shows an output when the signals V1 and V2 are applied to both input terminals of the exclusive OR of the phase difference comparison circuit 23. The output of the phase comparison circuit 23 is subjected to waveform conversion processing via an integration circuit 24 and an impedance conversion circuit 25, and is output as the entire magnetic body detection circuit 20.

In the circuit configuration shown in FIG. 3, an example has been described in which the output of the resonance circuit (detection circuit) is extracted as a phase difference and the phases are compared. However, instead of extracting the output of the detection circuit as the phase difference, for example, As shown in FIG. 7, the amplitude of one or both of the currents flowing through the first and second resonance circuits caused by the change in the inductance of the first coil and the second coil due to the change in the magnetic permeability of the magnetic body in the coil proximity region. The change may be extracted as an output through a detection circuit.

Next, the coil structure of the toner concentration detecting device, which is a feature of the present invention, will be described below with reference to FIGS. FIG. 8 is a view showing a ribbon-shaped parallel wire in which two conductive wires are covered with an insulating coating and integrated, and a coil structure in which the parallel wire is wound up. FIG. 9 is a diagram showing a fused wire and the fused wire wound up. FIG. 3 is a diagram showing a coil structure in which the present invention is used. FIG. 10 is an exploded view of a structure in which a coil is mounted on a magnetic core.
1 is a diagram showing the structure of a U-shaped coil in a ribbon-shaped integrated parallel line, FIG. 12 is an exploded view of a structure in which a U-shaped coil is mounted on a magnetic core, and FIG. It is a figure which shows the coil structure which turned both sides of the circular coil of the parallel wire of the shape integrated into the coil center part.

In FIG. 8, as shown in FIG.
Has the terminals of L1-1 and L1-2, and the second coil has the terminals of L2-1 and L2-2. (2) is a side view, (3) is a plan view of the coil, and (4) is a cross-sectional view of a ribbon-shaped parallel wire obtained by covering two conductors with an insulating film and integrating them. As shown in FIGS. 8 (2) and 8 (3), the parallel conductors are vertically arranged and wound outward in one step (as shown in FIG. 8 (4), one ribbon-shaped parallel wire is arranged vertically). And wound sequentially) (in the figure, the coil is wound from the inside to the outside, but the reverse is also possible). One of the features of the present invention is that the wound coil shown in (3) of FIG. 8 has a substantially rectangular shape.

The T sensor facing the stirring screw shown in FIG. 2 is the toner concentration detecting device, and the flat portion (the surface parallel to the paper) of the coil shown in FIG. 8 (3) faces the stirring screw shaft. Are arranged as follows. In FIG. 2, a stirring screw is exemplified as the developer stirring member. However, the invention is not limited thereto, and a stirring roller may be used. As shown in FIG. 2, both the stirring screw (having a helical blade around the rotation axis) and the stirring roller (having the blade along the rotation axis) have their rotation axes arranged in a direction perpendicular to the paper surface. The structure of the stirring screw described in JP-A-11-223620 is applicable.

When a rectangular coil showing the features of this embodiment is mounted on the opposing surface of the stirring member (stirring roller, stirring screw, etc.), the direction of the rotation axis of the stirring member coincides with the longitudinal direction of the rectangular coil. Arrange the coils so that As described above, the present embodiment is based on the premise that the rotary member is provided for mixing and stirring or transporting the developer, and the toner concentration detecting device is arranged to face the peripheral surface of the rotary member. Things.

As a specific example, two parallel lines are vertically arranged in a single step, for example, wound 60 times without a magnetic core, and the outer length in the coil longitudinal direction is 10 to 20 mm (for example, 15 mm).
Then, a structure in which the outer length in the coil short direction is 4 to 8 mm (6 mm as an example) is used. A coil structure may be formed by winding a ribbon-shaped parallel wire in which an insulating film is applied on a conductive wire using a copper wire or an aluminum wire having an appropriate diameter around a non-magnetic bobbin (the bobbin is not shown in FIG. Coil support for winding the conductor).

FIG. 8 shows one ribbon-shaped parallel wire in which two conductors are paired, but instead, two fusion-bonded wires are vertically fused to form a pair (as an example, By winding while applying heat, the fused conductors are joined together),
The same function as that of the ribbon-shaped parallel line shown in FIG.

The coil structure according to the present embodiment has a rectangular shape as an example in FIG. 8 (3). However, the present invention is not limited to this shape, and the aspect ratio of the coil is 1: 1 (ie, circular or square). It is characterized by an oval structure including an elliptical shape, which is different from the one described above. The technical significance of adopting this structure will be described later.

FIG. 9 shows the structure of the fusion-bonded lead wire. The lead wire uses a copper wire, and the insulating film uses an insulating material containing polyurethane. The fusion coating is made of a thermoplastic resin or a thermosetting resin, and the thermoplastic resin includes a polyamide resin, a butyral resin, and an epoxy resin. In the thermosetting type, the coil is heated and cured after winding. FIG. 9 (2) shows that the two fusion conductors are arranged vertically to form a pair of fusion conductors, and the pair of fusion conductors are wound horizontally to form an elliptical coil. ing.

As described above, the embodiment of the present invention corresponds to FIG.
9 or a pair of fusion conducting wires obtained by vertically fusing two fusion conducting wires shown in FIG. 9 to form a coil, and the formed coil has a rectangular or elliptical shape. One of the features is to use coil shapes having different aspect ratios including shapes. One of the features of the present embodiment is that the coils are arranged so that the longitudinal direction of the rectangular coil as an example coincides with the rotation axis direction of the rotating member including the stirring roller or the stirring screw.

As the overall structure of an image forming apparatus or a digital copying machine having a developing device is reduced in size, the developing device is also required to be reduced in size, and a vertical cross section of a rotating shaft of a stirring screw or a stirring roller in the developing device (FIG. 2) Is also required to be small. That is, the size of the stirring screw or the stirring roller in the rotation direction is reduced.

Therefore, by making the coil a rectangular or elliptical shape, the inductance required for the coil is secured, and the coil is further shortened in the rotation direction of the rotating member, so that the toner density detecting device and, consequently, the developing device can be used. This can contribute to downsizing. In addition, by arranging the coil in the longitudinal direction so as to coincide with the axial direction of the rotating member, the number of magnetic fluxes of the coil can be sufficiently secured, so that the toner density detection performance is improved.

Further, when a stirring screw is used as the rotating member, the developer is transported in the direction of the rotation axis. here,
In a conventional round coil, the detection width in the rotation axis direction is short and ripples (rotational pulsations) of the rotation cycle are generated. Are averaged, and stable toner density detection becomes possible. As a specific example when a stirring screw is used, the ripple can be most averaged if the length of the rectangular or elliptical coil in the longitudinal direction is approximately half the screw pitch.

In addition, since the first coil and the second coil are wound around the same position, the first and second inductances are substantially equal, and the magnetic coupling constant of both coils is large. Become. As a result, the accuracy of detecting the toner density close to the coil is improved.

Next, another coil structure relating to the present embodiment will be described. FIG. 10 shows a coil structure in which a coil composed of first and second coils is mounted on a magnetic core. In FIG. 10, the upper side of the coil is the surface facing the developer, and a magnetic core is formed on the opposite side so as to surround the coil (as shown). A magnetic circuit is formed by providing a protrusion on the magnetic core so as to fit into the hollow portion at the center of the coil. By providing the magnetic core, the magnetic resistance is reduced, and the number of turns of the coil can be reduced by that much, and the size can be reduced.

Another coil structure according to the present embodiment will be described. As shown in FIG. 11, a pair of one ribbon-shaped parallel wires or two fused conductors are vertically fused. A rectangular coil (as shown in (1) of FIG. 11) obtained by flatly winding the fusion-bonded conductor in one step is bent at a dashed line portion shown in (1) of FIG. Form a coil in the shape of a letter. The size of the stirring member in the rotation direction can be reduced by the amount of bending. here,
Although one ribbon-shaped parallel line or the like is wound horizontally in one step, the present invention is not limited to this, and it may be one in which a plurality of layers are vertically stacked and then wound horizontally. Further, if the coil shown in (1) of FIG. 11 is formed as a square coil and bent as shown in (2), the surface of the coil facing the developer becomes substantially rectangular, and the size can be reduced.

In addition, as shown in FIG. 12, if a magnetic circuit is formed by applying a magnetic core provided with a projection that fits into a hollow portion in the center of the coil to form a magnetic circuit, The number of times can be reduced and the size can be reduced.

Further, another coil structure according to this embodiment will be described. As shown in FIG. 13, a pair of ribbon-shaped parallel wires or two fusion-bonded wires are fused vertically. A circular coil (as shown in (1) of FIG. 13), which is formed by flatly winding a fusion-bonded wire in a single step, is interposed with an insulating spacer to form a single point shown in (1) of FIG. The coil is bent at the dashed line to form a U-shape, and the outer portion of the coil is bent toward the center of the coil as shown in (3) of FIG. 13 to form the entire structure of the coil. The size of the stirring member in the rotation direction can be reduced by the amount of the first bending, and the thickness in the coil thickness direction can be reduced by the second bending, so that the entire coil structure can be downsized. As a specific example of FIG. 13, the insulating spacer has a thickness of 0.1 to 3 mm (0.2 mm as an example).
And PET with a length of 20 mm in the longitudinal direction of (2) in FIG.
Using the (resin material name), the diameter of the circular coil shown in (1) of FIG. 13 is 10 to 20 mm (for example, 15 mm).
The length of the bending coil shown in (2) of FIG. 13 (the lateral length of (2) in FIG. 13) is 4 to 10 mm (6 m as an example).
m).

As described above, according to the coil structure according to the present embodiment, the toner concentration detecting device can be reduced in size, and the first coil and the second coil can be wound by one coil winding operation, so that the work is labor-intensive. Cost savings without cost.
Further, the variation in inductance between the first coil and the second coil is reduced, and a high-precision resonance circuit can be formed, so that the toner density detection performance is improved. Further, when a screw is used as the stirring member, the ripple of the rotation cycle is averaged, and stable toner concentration detection can be performed.

The above-described toner density detecting circuit is similar to that shown in FIG.
The present invention can be applied to an image forming apparatus provided with a developing device as shown in FIG. 1, and can be naturally applied to a digital copying machine including a printer and a scanner as shown in FIG.

Further, in the above description, the fact that the magnetic material containing the developer is arranged near the first coil and the second coil to change the inductance according to the magnetic permeability is used. However, the present invention is not limited to this, and it is also possible to dispose a conductor in a region close to both coils and use the fact that the coil inductance changes due to the effect of the magnetic field due to the eddy current in the conductor due to the magnetic flux from the coil. That is, a method utilizing the fact that the inductance changes according to the electric conductivity may be used.

Although the description has been given of the case where the developer 26 is provided near the first and second coils L1 and L2, the developer 26 may be provided near one of the coils.

Further, in the above description, the detection of the toner concentration of the developer has been described. However, the present embodiment is not limited to this, and the change in the coil inductance when the magnetic material or the magnetic powder drops below a predetermined level is described. The present embodiment can also be applied to the detection of the level of a magnetic substance or a magnetic powder by detecting, and the detection of presence / absence of a magnetic substance or a magnetic powder.

[0055]

According to the present invention, the size of the toner concentration detecting device in the rotation direction of the stirring screw or the stirring roller can be reduced. Furthermore, by arranging the coil longitudinal direction to coincide with the axial direction of the rotating member,
Since the number of magnetic fluxes of the coil can be sufficiently secured, the toner density detection performance is improved.

Further, when a stirring screw is used as the rotating member, ripples in the rotation cycle are averaged, and stable toner concentration detection can be performed.

Further, since the first coil and the second coil are wound around the same position, the first and second inductances are substantially equal, and the magnetic coupling constant of both coils is large. . As a result, the accuracy of detecting the toner density close to the coil is improved. Furthermore,
Since the first coil and the second coil can be wound by one coil winding operation, no labor is required and the cost is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of an electrophotographic copying apparatus to which a magnetic body detection device according to an embodiment of the present invention is applied.

FIG. 2 is a diagram illustrating a configuration of a developing device provided with a toner density sensor.

FIG. 3 is a diagram illustrating an example of a circuit configuration of a toner concentration detection device according to the exemplary embodiment.

FIG. 4 is a diagram illustrating another example of a circuit configuration of the toner density detection device according to the embodiment.

FIG. 5 is a diagram for explaining basic functions related to the toner density detection device according to the embodiment.

FIG. 6 is a diagram showing signal waveforms in a circuit configuration according to the present embodiment.

FIG. 7 is a diagram illustrating an example regarding output extraction of the toner density detection device according to the embodiment.

FIG. 8 is a view showing a ribbon-shaped parallel wire in which two conductive wires are covered with an insulating film and integrated, and a coil structure in which the parallel wire is wound up.

FIG. 9 is a diagram showing a fusion conducting wire and a coil structure in which the fusion conducting wire is wound up.

FIG. 10 is an exploded view of a structure in which a coil is mounted on a magnetic core.

FIG. 11 is a view showing the structure of a U-shaped coil in a ribbon-shaped integrated parallel line.

FIG. 12 is an exploded view of a structure in which a U-shaped coil is mounted on a magnetic core.

FIG. 13 is a diagram showing a coil structure in which both sides of a ribbon-shaped integrated parallel-line circular coil are folded back to the center of the coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reading part 2 Lamp 3 CCD 4 Amplifier 5 A / D conversion part 6 Image processing part 8 Pseudo correction 9 Filter 10 γ correction 11 Gradation processing 12 Image formation part 13 Writing part 14 Exposure 15 Charger 16 Developing sleeve 17 Feeding Tray 20 Toner concentration detection circuit 21 Oscillation circuit 22 Resonance circuit (detection circuit) 23 Phase comparison circuit 24 Integration circuit 25 Impedance conversion circuit 26 Developer

Continued on front page F term (reference) 2G053 AA29 AB07 BA05 BC14 CA03 CB25 DA01 2H077 AB02 AC03 AD06 AD13 DA10 DA42 DA51 DA54 DA86 EA03 EA21

Claims (13)

[Claims] A coil provided in proximity to a developer containing magnetic powder called a carrier and colored particles called a toner;
In the toner concentration detecting device for detecting a toner concentration indicating a mixture ratio of the toner and the carrier of the developer using the coil, the coil has a shape including a rectangle or an oval having a different aspect ratio. Toner density detection device. 2. A coil is provided in proximity to a developer containing magnetic powder called a carrier and colored particles called a toner,
In a toner concentration detecting device for detecting a toner concentration indicating a mixing ratio of a toner and a carrier of the developer using the coil, the coil has a shape including a rectangle or an oval having a different aspect ratio, and a length of the coil. A toner concentration detecting device, wherein the direction is arranged so as to coincide with the direction of the rotation axis of the developer stirring member. 3. The toner concentration detecting device according to claim 1, wherein a core having a high magnetic permeability is provided adjacent to the coil, and the core has a rectangular or oval shape. Concentration detection device. 4. A coil is provided in proximity to a developer containing magnetic powder called a carrier and colored particles called a toner,
In a toner concentration detecting device that detects a toner concentration indicating a mixing ratio of a toner and a carrier of the developer using the coil, the coil includes a circular, square, rectangular, or an oval wound coil body. A toner concentration detecting device having a U-shape formed by bending a circle. 5. The toner density detecting device according to claim 4, wherein a core having a high magnetic permeability is provided in an inner region surrounded by the U-shaped coil. 6. A coil is provided in proximity to a developer containing magnetic powder called a carrier and colored particles called a toner,
In a toner concentration detection device that detects a toner concentration indicating a mixture ratio of the toner and the carrier of the developer using the coil, the coil includes a spacer formed in a wound coil body having a circular, square, rectangular, or oval shape. A toner concentration detecting device having a shape in which both sides of a wound coil body are folded back toward the center of the coil with interposition. 7. The toner density detecting device according to claim 1, wherein the coil is formed by winding the coil around a bobbin. 8. The toner concentration detecting device according to claim 1, wherein the coil is a single parallel wire formed by covering two conductors with an insulating film and integrating them. A toner density detecting device, which is formed by winding a plurality of times in the direction of the developer facing surface. 9. The toner concentration detecting device according to claim 1, wherein the coil is formed by superposing each fusion-bonding lead having a fusion coating on the outermost side in the developer direction. A toner density detecting device, which is formed by winding and fusing each of the fusion-bonded wires, and winding the fusion-bonded wires a plurality of times in the direction of the developer-facing surface to fuse each of the fusion-bonded wires. 10. An image forming apparatus in which the toner density detecting device according to claim 1 is attached to a developing device. 11. A digital copying machine in which the toner density detecting device according to claim 1 is attached to a developing device. 12. A toner density detecting device for detecting a toner density indicating a mixing ratio of a toner and a carrier of the developer according to claim 1,
A magnetic body detection device for detecting a predetermined level of a magnetic body or the presence or absence of a magnetic body. 13. The toner concentration detecting device according to claim 1, wherein a conductor is arranged in place of the developer arranged in an area adjacent to the coil, and the presence or absence of the conductor is determined. Conductor detection device to detect.